Chapter 1.5

---

Vocabulary

---

Plates:a section of the lithosphere that slowly moves carrying pieces of the crust
Scientific Theory:a well tested theory
Plate Tectonics:the geological theory that states that pieces of the Earth's lithoshere are in constant movement
due to convection currents in the mantle
Faults:breaks in the Earth's crust where rocks have slipped passed each other
Transform Boundary:a place where two plates slipped pass each other, in opposite directions
Divergent Boundary:a place where two plates diverge, or move apart
Rift Valley:a deep valley that forms along a divergent boundary
Convergent Boundary:a place where two plates collide,come together,or converge

---

Outline

---

Theory of Plate Motion

• Wilson combined sea-floor speading and continental drift into a single theory
  • his theory states that the Earth's lithosphere is broken into pieces called plates
  • Theory includes that the plates are driven by convection currents in the mantle

Plate boundaries

• plates meet at a boundary
  • there are three different boundaries
    • transform,divergent,convergent

The Continents' Slow Dance

• plates move slowly
  • 2.5 cm a year, about same rate as fingernails grow
  • about 260 million years ago, continents were combined into pangaea
  • they broke at 225 million years ago

back to homepage